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March 21, 2011 -- Many lifestyle-related cancers disproportionately affect the poor, but new research finds the opposite to be true for the most lethal form of skin cancer: melanoma.

In a California study, non-Hispanic, white teens and young women living in the most affluent neighborhoods were nearly six times as likely to be diagnosed with melanoma as white teens and young women living in the poorest neighborhoods.

“That was a surprise to us,” says study co-researcher Christina A. Clarke, PhD, MPH, of Stanford University and the Cancer Prevention Institute of California. “We thought UV radiation exposure would be a more important predictor of melanoma risk than socioeconomic status, but that is not what we found.”

Rising Melanoma Rates for Young Women

Melanoma is caused by sun exposure. Fair-skinned people have the highest risk. More than 90% of all skin cancers in the U.S. occur in non-Hispanic whites.

Rates among white teenage girls and younger women have more than doubled over the past three decades and they continue to rise, while rates among teenage boys and young men plateaued after 1980, Clarke says.

Deadly invasive tumors and easily removable localized tumors are increasing among young, white women, suggesting that the increase is not solely the result of better surveillance and earlier diagnosis.

The newly published study is not the first to link higher socioeconomic status with an increased melanoma risk among white women, but it is the most rigorous.

By comparing melanoma cases reported to a statewide cancer registry with census data, the researchers were able to assess the socioeconomic status of the cases by neighborhood.

A total of 3,800 white women between the ages of 15 and 39 with melanomas detected between 1988 and 1992 and between 1998 and 2002 were included in the study. Most of the cancerous lesions were diagnosed and removed before they spread beyond the skin.

Melanoma rates increased over time, but the biggest increases were seen in teens and young women living in neighborhoods with the highest incomes.

Among women living in neighborhoods with the highest UV radiation levels, melanoma rates were 70% higher for those living in the highest income neighborhoods compared to the lowest.

The study was published online today, and it will appear in the July issue of Archives of Dermatology.

Why Wealth Is Linked to Melanoma

Clarke says the findings should help public health officials direct screening and education efforts aimed at preventing melanomas and other sun-related skin cancers.

“California is a sunny state, but we found that risk was not just related to living in a sunny area,” she says. “Women living in affluent, sunny areas may have different cultural norms or they may have more time to tan.”

Assistant dermatology professor Sherrif Ibrahim, MD, PhD, of the University of Rochester in New York says while young affluent women may take more tropical vacations or go to tanning salons more often than women who have less disposable income, they are also more likely to have health insurance and better access to medical care, which could largely explain the differences in risk.

“Melanoma rates are rising among young, light-skinned women regardless of socioeconomic status,” he says. “Increasing awareness among all groups should be the goal.”

Ibrahim supports legislative efforts to ban or severely restrict the access of teens to tanning salons.